A multi-sectional belt conveyor is constructed of a drive section and a plurality of driven sections, which can be added as required to lengthen the drive section. The location of the end of such a conveyor is changeable by adding or removing a driven section. Thus, this type of conveyor is desirable in applications having a temporary work station or a changeable destination. The drive section is provided with a motor, the weight and size of which causes that section preferably to be stationary or at least moved with difficulty. However, the driven sections can be made relatively much lighter in weight and more portable by deriving their required power from the motor associated with the drive section.
The power of the single motor is transmitted to the driven sections by use of a power transmission system. Many such systems are known, with the most common being the drive shaft systems and the belt drive systems. In the former, an interconnectable drive shaft runs the length of each section for transmitting power, and a power take-off device, such as a right angle drive, allows the drive shaft to independently operate each section of the belt. The drive shaft of each section connects to the drive shafts of the juxtaposed sections, efficiently transmitting power over the length of the assembled sections. In the latter, the conveyor belt itself transmits power over the length of each section and drives a power take-off device, typically a gear system, located at the end of each section. The power take-off device transmits power between the conveyor sections, while the belt transmits power over the length of each individual section. The latter type of transmission system is common, and the present invention is directed to improvements in such a system.
In a belt drive system, three areas present technical problems: the belt tension adjusting system, the power take-off system, and the conveyor section joining or latching system. These can be inter-related in structure and function. The belt tensioning system must provide an efficient translation of motion from the belt itself to the rollers that carry the belt. Typically, at one end of the conveyor section an external source, such as the power take-off from the preceding section, drives a drive roller and, in turn, the drive roller drives the belt. At the opposite end of the section, the belt powers a driven roller, which supplies power to a power take-off system for transmission to the next section. The belt tension is critical to the efficiency of power transmission between the belt and the drive or driven rollers.
The power take-off system must work in cooperation with the drive and driven rollers to transfer power between juxtaposed conveyor sections. The joining system and power take-off system must cooperate, as well, since the joining system establishes the spatial relationship between sections, which must be bridged by the power take-off system. The conditions where portable conveyors are used can increase the difficulties faced by these systems. For example, irregular floors, physical obstructions, and job requirements can lead to uneven or non-linear alignment between sections. Vertical angles, horizontal angles, or combinations of both might result between sections, placing difficult demands on the power take-off and joining systems.
A number of patents have addressed the problems of sectional conveyors powered from a single source. For example, U.S. Pat. No. 5,096,045 to Feldl teaches a conveyor having multiple unit sections that can be joined. The belt tensioning system employs a conventional belt tensioning idler roller on opposite side adjustment bolts, positionable to take up extra belt length along the bottom run. The power transmission system employs belt rollers at opposite ends of the section that drive the conveyor belt, and power is transmitted between sections by gears that interconnect the abutting end belt rollers. The latching system employs a bridge mechanism that carries the power transmission gears in protective boxed end units that are slotted to fit over the ends of the drive rollers. A latch plate locks the boxed end units in engagement with the drive roller spindles. While the systems shown in Feldl accomplish the desired results, there no provision for irregularities in the conveyor environment. For example, the bridge mechanism has no provision for uneven ground or floor surfaces or for lateral bending in the conveyor path. It would be desirable to have greater flexibility in the allowed methods of assembling the sectional conveyor.
U.S. Pat. No. 4,925,009 to Hill teaches a similar sectional conveyor in which the belt tensioning system employs a frame that holds the drive roller relative to a plank that supports the belt along most of its run. Threaded tightening bolts extend the frame with respect to the plank to tension the belt, although it appears the connection between the frame and plank is subject to looseness and misalignment. The power take-off system and joining system are integrated. Drive rollers of adjacent sections are connected by a roller chain that also travels over an idler sprocket carried on the frame's understructure. The chain is given proper tension by separating the sections, and hence the drive rollers, using pre-positioned slots that engage a flange. The integrated systems do not offer flexibility in the position of the adjoining sections.
A somewhat similar system is found in U.S. Pat. No. 2,563,427 to Scott, which shows the interconnection of two conveyor sections in which an end bearing of the two opposed end belt rollers is nested in a common stand. A mating coupler, employing gears connected by a roller chain, joins these two rollers to transmit power from section to section.
Other patents show variations in the construction of multi-sectional conveyors and other equipment. U.S. Pat. No. 4,046,248 to Goffredo et al. shows a system for connecting modules in alignment and transmitting power from a single drive source between the modules. U.S. Pat. No. 4,401,562 to Spugios shows a union between a conveyor unit and a parts separator. Both pieces of equipment are powered through a drive gear in the conveyor unit, which drives the separator via an idler gear. U.S. Pat. No. 1,815,135 to Williams discloses another sectional conveyor that transmits power via idler gears. U.S. Pat. No. 1,603,633 to Nelson shows a sectional conveyor in which sections am joined by hooks and power is transmitted through an idler gear between sections. Finally, U.S. Pat. No. 1,427,890 to Zesbaugh shows a sectional conveyor in which a motor drives an end roller by powering a drive shaft that runs along side the belt.
It would be desirable to have a multi-section conveyor in which the belt tension adjustment was both simple and reliable. Further, the belt tension adjustment should not introduce looseness or misalignment within the individual section.
Further, it would be desirable to have a conveyor section joining system that accommodates irregularities in the path of the assembled sections.
Still further, it would be desirable to have a power transmission system between sections that can accommodate the variations in path direction.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the multi-section conveyor of this invention may comprise the following.